# Kinetics: Rate Law

i am clarifying this is not an assignemt is just practice questions. It was part of an old test that the teacher gave to us to practice .

This are practice questions

1. Calculate deltaH for the reaction P4O10 + 6 PCl3 ----? 10 Cl3PO

From

P4 + 6 Cl2 -----> 4 PCl3 deltaH = -1225.6 kJ

P4 + 5 O2 -----> P4O10 deltaH = -2967.3 kJ

PCl3 + Cl2 -----> PCl5 deltaH = -84.2 kJ

PCl3 + ½ O2 ---> Cl3PO deltaH = -285.7 kJ

2. Experiment

................[HgCl2]M............ [C2O4-2]M........ Rate(M/sec)

1..................0.105....................0.15...............1.8 x 10-5

2 .................0.105....................0.30...............7.2 x 10-5

3...................0.052...................0.30...............3.5 x 10-5

4..................0.052....................0.15...............8.9 x 10-6

5 .................0.200....................0.45.....................X

6..................0.35..........................y.................5.0 x 10-5

a) Determine the rate law

b) Calculate k

c) Determine the values for X and Y

3. Butadiene, C4H6, dimerizes to C8H12 with a 1st order rate constant of 0.014 L/mol sec. Starting with 0.025 M

a) What will be the concentration after 3.00 minutes?

b) How long will it take the concentration to drop to 0.0065 M?

#### Solution Preview

1.

6PCl5 -> 6PCl3+6Cl2 (-6*(III))

10PCl3+5O2 -> 10Cl3PO (10*(IV))

P4O10 -> P4+5O2 (-(II)).

(I)-6*(III)+10*(IV)-(II): we could obtain our reaction.

Delta H = -1225.6-6*(-84.2)+10*(-285.7)-(-2967.3)= -610.1 kJ

2.

a)

When [C2O4-2] ...

#### Solution Summary

The expert calculates deltaH for a reaction using kinetic rate laws.